You don't. The sensor and necessary wiring is not installed in the LX and there is no 'kit' available from Honda to enable this option.
The 2011 Honda Civic has 16 valves.
The 2011 Honda Civic has a 5-speed manual.
The 2011 Honda Civic has an inline 4 engine.
The 2011 Honda Civic is a gas-powered vehicle.
The curb weight of the 2011 Honda Civic is 2588 lbs..
The 2011 Honda Civic has single overhead cam (SOHC).
The height of the 2011 Honda Civic is 4 ft. 7 in. (55 in.).
The 2011 Honda Civic's turning circle is 35.4 ft..
The 2011 Honda Civic is 14 ft. 7.5 in. (175.5 in.) long.
The 2011 Honda Civic runs on regular unleaded.
The 2011 Honda Civic has 35.1 in. of rear head room.
The 2011 Honda Civic has 42.6 in. of front leg room.